The HR 120 is a multipurpose compact drilling rig suitable for medium to large diameter drilled shafts for drilling in any kind of soil by using a rotary system with kelly bar, augers and buckets. The HR 120 utilizes friction or interlocking kelly bars for various depths. The cabin has been designed to offer maximum efficiency and comfort for the operator which can also be equipped with an electronic depth counter, automatic levelling system, and air conditioning and heating system. The HR 120 comes mounted on expandable crawlers, but can even be mounted on a truck. In either version, the kelly bar does not have to be removed for transport, which decreases the transport costs, and set-up time on the jobsite. The HR 120 can be configured for works for Bored piles, Continuous Flight Auger (CFA), and even Diaphragm Walls by use of kelly.